 
   Two additional options may be passed in the spec:
 
-  * `:id` - a unique identifier for the scheduled job
-  * `:singleton` - a boolean denoting the job's behavior in a cluster [true]
+  * :id - a unique identifier for the scheduled job
+  * :singleton - a boolean denoting the job's behavior in a cluster [true]
 
-  If called with an `:id` that has already been scheduled, the prior job
+  If called with an :id that has already been scheduled, the prior job
   will be replaced. If an id is not provided, a UUID is used instead.
 
   The return value is a map of the options with any missing defaults

  ```

  Optional helper functions can be combined to create the spec as well:

  ```
  (schedule #(println \"I'm running!\")
    (-> (in 5 :minutes)

  "Schedules a function to run according to a specification map
  comprised of any of the following keys:

  * :in - a period after which f will be called
  * :at - a time after which f will be called
  * :every - the period between calls 
  * :until - stops the calls at a specific time
  * :limit - limits the calls to a specific count
  * :cron - calls f according to a [Quartz-style](http://quartz-scheduler.org/documentation/quartz-2.2.x/tutorials/tutorial-lesson-06) cron spec

  Units for periods (:in and :every) are milliseconds, but can
  also be represented as a keyword or a vector of number/keyword
  pairs, e.g. `[1 :week, 4 :days, 2 :hours, 30 :minutes, 59 :seconds]`.

  Date/Time values (:at and :until) can be a `java.util.Date`,
  millis-since-epoch, or a String in `HH:mm` format.

  For example:
  ```
  (schedule #(println \"I'm running!\")
    {:in [5 :minutes]
